This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No.P2001-204749, filed on Jul. 5, 2001 and No.P2001-214463, filed on Jul. 13, 2001; the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fusion splicing method and device for optical fibers, specifically, ribbon optical fibers (having a tape-shaped structure) capable of obtaining a good splice state of the ribbon optical fibers by fusing and splicing the ribbon optical fibers with an approximately uniform amount of heat applied to all of bare fibers of the ribbon optical fibers.
2. Description of the Related Art
In a fusing and splicing process for optical fibers, specifically, ribbon optical fibers having a tape-shaped structure, the bare fibers (which are distal ends of the optical fibers, each bare fiber is made up of a core and a clad where a coated material has been eliminated) to be spliced together are arranged and aligned, in opposite direction to each other, on a V-groove block in a fiber setup stage. Then, an aerial discharge (arc discharge) is generated between a pair of electrode rods. The bare fibers of the ribbon optical fibers are thereby fused and spliced together. This is called the fusing splicing method.
In the fusing and splicing method, when the width of the ribbon optical fibers (of a tape-shaped structure) is large, it becomes difficult to heat all of the bare fibers at a uniform temperature. This causes dispersion of the spliced optical fibers.
Dispersion of the spliced optical fibers occurs for the following reason. For example, as shown in FIG. 1, when an arc discharge occurs between a pair of the discharge electrode rods 1 in the atmosphere under a normal condition, the temperature distributions in the upper and lower haves of a discharge area 2 have a symmetrical shape, and a rapid temperature change occurs around the electrode rods 1. The width W1 (or a length) of a region 2a, which is separated in position from a pair of the discharge electrode rods 1 and where the change of the temperature is relatively uniform, does not become long.
This problem does not occur when the number of the bare fibers in a ribbon optical fiber is relatively small. However, when this number is large (for example, when the number is not less than twenty-four) it becomes difficult to set the entire of the bare fibers xe2x80x9cfxe2x80x9d of the ribbon optical fibers into the uniform temperature region 2a. This means it is difficult to perform a uniform heating for all of the cores in the ribbon optical fiber.
In such a case where a variation of the heating temperature happens, a lack of the holding strength occurs in the spliced part between the optical fibers or a splice loss occurs at the spliced part in the ribbon optical fibers.
In order to eliminate the drawbacks described above included in the related art, the following technique has been disclosed in the Japanese patent publication No. H03-229206 in which a magnetic field applying means of a complicated structure is mounted in the device, and it generates and applies a magnetic field to an arc-discharge region between the discharge electrode rods. The temperature distribution in the arc-discharge is thereby controlled so that all of the bare fibers of ribbon optical fibers to be spliced are heated uniformly. The optical fibers of the ribbon optical fibers are spliced together.
However, the magnetic field applying means in the above related art has following drawbacks.
First, it is necessary to install one or more additional coils of a relatively large size for generating the magnetic field around the discharge electrode rods. It is further necessary to mount a power source means for applying electric power to those coils. This causes the device to become a complicated structure, the manufacturing cost of the device becomes high, and the entire size of the device becomes large.
Furthermore, there is a possibility that the electrode rods erroneously discharge around the coils of the magnetic generation means. Moreover, it is necessary to install a shield means for eliminating erroneous operation of the device because the coils generate a strong magnetic field.
Further, the generation of the magnetic field in the coils increases the power consumption of the device.
Accordingly, an object of the present invention is, with due consideration to the drawbacks of the related art, to provide a fusion splicing method and device for optical fibers, specifically, ribbon optical fibers, having an electric potential applying section of a simple configuration, for example having a fiber clamp function, mounted on a fiber setup stage in which bare fibers of the ribbon optical fibers are set, or having an electric potential applying section comprising a conductor plate of a simple configuration and the like under the fiber setup stage. Thereby, the method and device can control a distribution of the discharge optimally, and can heat all of the bare fibers of the ribbon optical fibers with an approximately uniform temperature, and can splice the both ribbon optical fibers precisely and completely.
In order to achieve the above object of the present invention, there is provided a fusion splicing method for optical fibers having following steps, arranging bare fibers of ribbon optical fibers, in opposite direction to each other and to be spliced together, on a fiber setup stage, generating an electric field by applying a voltage to an electric potential applying section mounted on the fiber setup stage, and fusing and splicing the bare fibers together by controlling that all of the bare fibers are set in a uniform temperature area in a discharge area generated by a discharge between a pair of discharge electrode rods and by applying the electric field to the discharge area.
According to an embodiment, a fusion splicing device for optical fibers has a fiber setup stage on which ribbon optical fibers to be spliced are arranged in opposite direction to each other, an electric potential applying section for generating an electric field, arranged on the fiber setup stage, having a function of fiber clamps to clamp the ribbon optical fibers, and made up of a conductive material, and a pair of discharge electrode rods for generating a discharge in order to fuse and splice bare fibers of the ribbon optical fibers on the fiber setup stage. In the device, in order to fuse and splice the ribbon optical fibers together, the electric field is generated by controlling a voltage to be applied to the electric potential applying section according to the number of the bare fibers of the ribbon optical fibers so that all of the bare fibers are set in a uniform temperature area in the discharge area obtained by the discharge.
Still further, according to an embodiment, a fusion splicing method for optical fibers has following steps, arranging corresponding bare fibers of ribbon optical fibers, in opposite direction to each other, to be spliced together on a fiber setup stage, generating an electric field by applying a voltage to an electric potential applying section mounted under the fiber setup stage, and fusing and splicing the bare fibers together by controlling that all of the bare fibers are set in a uniform temperature area in a discharge area generated by a discharge between a pair of discharge electrode rods and by applying the electric field to the discharge area.
Still further, according to an embodiment, a fusion splicing device for optical fibers has a fiber setup stage on which ribbon optical fibers to be spliced are arranged in opposite direction to each other, an electric potential applying section for generating an electric field, arranged under the fiber setup stage, and a pair of discharge electrode rods for generating a discharge in order to fuse and splice bare fibers of the ribbon optical fibers on the fiber setup stage. In the device, in order to fuse and splice the ribbon optical fibers together, the electric field is generated by controlling a voltage to be applied to the electric potential applying section according to the number of the bare fibers of the ribbon optical fibers so that all of the bare fibers are set in a uniform temperature area in the discharge area obtained by the discharge.
The above and other features and advantages of this invention and the manner of realizing them will become more apparent, and the invention itself will best be understood, from a study of the following description and attached claims, with reference had to the attached drawings showing some preferable embodiments of the invention.